Flash based mass storage devices are used to store very large amounts of content, such as pictures and music or software programs. Examples of these mass storage devices include memory cards, universal serial bus (“USB”) flash drives, flash based music and/or video players, and other portable computing devices that rely on flash for the mass storage of content or files.
User files are frequently updated and modified. This is particularly the case when dealing with photos, music, and documents. Flash memory has a limited number of read/write cycles, and a great deal of research and development has gone into distributing the cycles among the flash memory cells in order to maximize the lifespan and reliability of the devices. For instance, wear leveling techniques such as those taught in U.S. Pat. No. 6,230,233 entitled “Wear Leveling Techniques For Flash EEPROM Systems” to Lofgren et al., U.S. Pat. No. 5,268,870 entitled “Flash EEPROM System and Intelligent Programming and Erasing Methods Therefore” to Harari, PCT Publication No. WO2004040578A2 entitled “Wear Leveling In Non-Volatile Storage Systems” to Chang et al., and U.S. Patent Publication No. 20040083335A1, entitled “Automated Wear Leveling In Non-Volatile Storage Systems” to Gonzalez et al., which are hereby incorporated by this reference in their entireties, are commonly implemented in these devices. These techniques generally involve changing the logical/physical mapping so that physical locations of the memory are used roughly the same amount.
In addition, as the usage of flash based mass storage devices is proliferating, the number of different things that can be done with them is also increasing.
Therefore, there exists a need for a new device operating system architecture that provides flexibility to store and run a wide range of firmware that can be updated and changed to accommodate the range of increasing functionality. In addition to being flexible, this architecture must provide a highly secure and reliable environment for both firmware and content. As is always the case, all of this should be done for the lowest possible cost, using standard components whenever possible.